H8 size battery install in a 2015 Passat

Jetta_Pilot

Top Post Dawg
Joined
Apr 14, 2005
Location
West Hill, Ont. Nov.2nd in Mexico till April 27th
TDI
2015 Passat Highline TDI Candy White (SEL Premium) long gone 2002 Jetta TDI
When I changed my AGM battery I lost the correct time and the then current trip meter reading and nothing else. Not worth the effort for a "memory minder".

BTW: An AGM battery acts more like a deep cycle battery, it can be pulled down without ill effects.
 

BKmetz

Administrator, Member #10
Staff member
Joined
Sep 25, 1997
Location
Illinois
TDI
2015 Passat, titanium beige, 6MT
When I changed my AGM battery I lost the correct time and the then current trip meter reading and nothing else. Not worth the effort for a "memory minder".
That's only if you work on your VW. My 4 boys currently own Chevy, Hyundai, Toyota, and Ford. I have had the alarm system go off and have had other annoying stuff happen when I disconnected the battery for various reasons and didn't have a memory minder.

:)
 

93celicaconv

Veteran Member
Joined
May 22, 2013
Location
Wisconsin
TDI
Turned in my 2010 Jetta TDI Cup Edition to VW, DSG, Nav, Sunroof / Replaced with a 2015 Passat TDI SEL Premium
Thanks for all the help, BKmetz & Oilhammer. Really appreciate it.

BTW, I measured my battery voltage on the 2015 Passat TDI this morning, cold, after not being run since the previous evening - engine off - measurement was 12.16V.

After starting, it went up to 14.6V. Immediately after shutting the engine down today after a 100+ mile trip with no stops, about 10 minutes after engine shutdown, battery voltage was 12.29V. The battery voltage should have been higher that 12.29V after this long trip event, right?

My 1993 Celica convertible had the battery charged 2 weeks ago and the negative cable disconnected for winter storage. Its a 2016 lead acid battery. I checked the voltage on it today also - it measured 12.88V. I'm suspecting that means this battery is at least good as far as holding a good voltage, whereas my OEM Passat battery no longer appears to be as healthy. Would like to hear your thoughts.
 

soot1

Veteran Member
Joined
Nov 6, 2009
Location
Houston, TX
TDI
Currently none. Formerly: 2010 VW Jetta TDI 6M, 1993 Dodge Ram W250 Cummins 5M 4WD, 1990 VW Jetta Diesel 5M, 1986 VW Jetta Diesel 5M, 1980 VW Uabbit Diesel 4M. Currently driving 2018 Toyota 4Runner SR5 4WD.
Thanks for all the help, BKmetz & Oilhammer. Really appreciate it.

BTW, I measured my battery voltage on the 2015 Passat TDI this morning, cold, after not being run since the previous evening - engine off - measurement was 12.16V.

After starting, it went up to 14.6V. Immediately after shutting the engine down today after a 100+ mile trip with no stops, about 10 minutes after engine shutdown, battery voltage was 12.29V. The battery voltage should have been higher that 12.29V after this long trip event, right?

My 1993 Celica convertible had the battery charged 2 weeks ago and the negative cable disconnected for winter storage. Its a 2016 lead acid battery. I checked the voltage on it today also - it measured 12.88V. I'm suspecting that means this battery is at least good as far as holding a good voltage, whereas my OEM Passat battery no longer appears to be as healthy. Would like to hear your thoughts.
Take your Passat to a VW dealer and have them do a quick load test, it is so simple and quick they did it for free for me once when I still owned my Jetta. The instrument they used printed a slip that showed how good the battery was, and how much life it has left. If the battery voltage is 12.29V after charging, it is on its way out. It should be in the same range as your Celica battery, above 12.8V. If you store battery during winter, it is a good idea to keep it in a cool place, but protect it from temperatures below 32F, and check the terminal voltage once a month. If it checks below 12.6V, hook it up to a charger and bring the voltage back to 12.8V.
 

93celicaconv

Veteran Member
Joined
May 22, 2013
Location
Wisconsin
TDI
Turned in my 2010 Jetta TDI Cup Edition to VW, DSG, Nav, Sunroof / Replaced with a 2015 Passat TDI SEL Premium
Take your Passat to a VW dealer and have them do a quick load test, it is so simple and quick they did it for free for me once when I still owned my Jetta. The instrument they used printed a slip that showed how good the battery was, and how much life it has left. If the battery voltage is 12.29V after charging, it is on its way out. It should be in the same range as your Celica battery, above 12.8V. If you store battery during winter, it is a good idea to keep it in a cool place, but protect it from temperatures below 32F, and check the terminal voltage once a month. If it checks below 12.6V, hook it up to a charger and bring the voltage back to 12.8V.
I previously did, soot1. It was checked during its 40,000 mile maintenance service (the major one, which also included a warranty-covered fuel lift pump (fuel pump in fuel tank) replacement due to loud humming noise and low lift pressure). The test back from VW service as the battery was good.

Last night, I put my smart charger on the battery (I normally just use my old 10A charger for my flooded batteries). When it started the checking process, it stated the battery was at 25% or less of its capacity, and started the charge process. That checks out with the low voltage I measured, and if everything was good, it should not have been that low after a non-stop 100+ mile drive.

But, this morning, the battery level was up to 100%. So I'm going to let the battery settle for a few hours now and see what the voltage is about 4 hours after charger removal.

All this just isn't making sense to me.
 

Jetta_Pilot

Top Post Dawg
Joined
Apr 14, 2005
Location
West Hill, Ont. Nov.2nd in Mexico till April 27th
TDI
2015 Passat Highline TDI Candy White (SEL Premium) long gone 2002 Jetta TDI
Now and in the foreseeable future I do not anticipate to be in freezing temperatures. The coldest my H8 AGM battery has seen is about 5° C or 40°F and it cranks the engine beautifully.
Now where I spend my winters the daytime temperatures can go into the mid 90°sF or the mid 30°sC and it's nice to have a completely sealed battery without any liquid losses sitting in the heat.
 

93celicaconv

Veteran Member
Joined
May 22, 2013
Location
Wisconsin
TDI
Turned in my 2010 Jetta TDI Cup Edition to VW, DSG, Nav, Sunroof / Replaced with a 2015 Passat TDI SEL Premium
Just an update on my 2015 Passat OEM battery. Charged it on smart charger, which includes pulse phase desulfication, for 24 hrs - after disconnect, voltage on battery was 12.69V (should have been 12.90V). Then it sat for a week while I was on a trip, never started after the charging process, doors not even opened in between. After sitting a week, battery voltage was down to 12.43V (which is about 50% of rated capacity available). So I think the battery has weakened, doesn't look like this loss can be recovered. Question is if a battery that has about 50% of original capacity at its best can make it through the cold Wisconsin winter or not. I'll likely be replacing it with a VW OEM lead-acid battery right around the Christmas / New Year's Holiday.
 

BKmetz

Administrator, Member #10
Staff member
Joined
Sep 25, 1997
Location
Illinois
TDI
2015 Passat, titanium beige, 6MT
...on cars that have the module. The Gateway installation list will have this information, but the NMS doesn't. And to follow up with the [clueless] dealer comment: the Volkswagen Phaeton has one, so they DID sell a car that requires this be input. :p
LOL. My local dealership never sold any Phaetons. I remember talking to the old parts manager (now retired) about Phaetons. He said there was one in the area, that whenever it was in the shop it was usually for some annoying electrical issue, and everyone hated working on it.

On a related note, everyone there loved driving the W8 Passat 4Motion, and everyone hated working on it.

:)
 
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